Channel bonding in passive optical networks

ABSTRACT

An apparatus in a passive optical network (PON) is configured to modify a preamble of a data packet to include channel bonding information. The apparatus may further fragment the data packet into a plurality of data frames and transmit the fragmented data frames through multiple channels. The channel bonding information may be used to identify different channels and to identify data frames transmitted through each channel.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 15/259,777 filed Sep. 8, 2016 by Duane Remein, et al., andtitled “Channel Bonding in Passive Optical Networks,” which claimspriority to U.S. provisional patent application No. 62/215,862 filedSep. 9, 2015 by Duane Remein, et al., and titled “Channel Bonding inEthernet Access Networks,” both of which are herein incorporated byreference in their entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO A MICROFICHE APPENDIX

Not applicable.

BACKGROUND

A passive optical network (PON) is one system for providing networkaccess over “the last mile,” which is the final portion of atelecommunications network that delivers communication to customers. APON is a point-to-multipoint (P2MP) network comprised of an optical lineterminal (OLT) at a central office (CO), an optical distribution network(ODN), and optical network units (ONUs) at the user premises. PONs mayalso comprise remote nodes (RNs) located between the OLTs and the ONUs,for instance at the end of a road where multiple customers reside.

In recent years, time-division multiplexing (TDM) PONs such asgigabit-capable PONs (GPONs) and Ethernet PONs (EPONs) have beendeployed worldwide for multimedia applications. In TDM PONs, the totalcapacity may be shared among multiple users using a time-divisionmultiple access (TDMA) scheme, so the average bandwidth for each usermay be limited to below 100 megabits per second (Mb/s).

Wavelength-division multiplexing (WDM) PONs are considered a verypromising solution for future broadband access services. WDM PONs canprovide high-speed links with dedicated bandwidth up to 10 gigabits persecond (Gb/s). By employing a wavelength-division multiple access (WDMA)scheme, each ONU in a WDM PON is served by a dedicated wavelengthchannel to communicate with the CO or the OLT. Next-generation PONs(NG-PONs) and NG-PON2s may include point-to-point (P2P) WDM PONs(P2P-WDM PONs), which may provide data rates higher than 10 Gb/s.NG-PONs and NG-PON2s may also include time- and wavelength-divisionmultiplexing (TWDM) PONs, which may also provide data rates higher than10 Gb/s.

TWDM PONs may combine TDMA and WDMA to support higher capacity so thatan increased number of users can be served by a single OLT withsufficient bandwidth per user. In a TWDM PON, a WDM PON may be overlaidon top of a TDM PON. In other words, different wavelengths may bemultiplexed together to share a single feeder fiber, and each wavelengthmay be shared by multiple users using TDMA.

SUMMARY

As demand for higher data transmission rates rise, it may be necessaryfor PON systems to operate over multiple wavelengths, such as two orfour 25 Gigabits per second (Gb/s) wavelengths. To this end,conventional PONs may employ an approach such as link aggregation inwhich multiple links may be combined to increase throughput as comparedto transmissions over a single link. However, such approaches typicallydo not utilize the increased bandwidth provided by the aggregated linksin an efficient manner. For instance, conventional link aggregationschemes may utilize about 60% of the aggregated link capacity, or even alesser percentage in some cases. The concepts disclosed herein providean inverse multiplexing scheme that involves modifying a preamble suchthat aggregated bandwidth may be used more efficiently, while reducingoverall latency in PON systems.

In an embodiment, the disclosure includes a method implemented at atransmitter in a passive optical network (PON). The method includes thetransmitter modifying a preamble of a data packet to include anindicator associated with at least one lane to be used to transmit thedata packet. The method further includes the transmitter fragmenting thedata packet into frames, and transmitting the frames over a plurality oflanes, where the indicator is configured to identify a first laneselected from the plurality of lanes and to identify at least one frametransmitted over the first lane.

In some embodiments, the method includes replicating the indicator intoeach lane within the plurality of lanes in response to fragmenting thedata packets into frames. In one or more embodiments, each indicator isconfigured to identify a respective set of frames transmitted over alane in which that indicator has been replicated. In one or moreembodiments, each indicator is further configured to indicate thatframes within the respective set of frames form part of the data packet.In one or more embodiments, the replicated indicators are configured toidentify at least one of: each lane used to transmit the frames; framestransmitted over each lane; each frame associated with the data packet;and a lane order occupied by a particular frame. In one or moreembodiments, the transmitter includes a reconciliation sublayer (RS),with the RS modifying the preamble to include the indicator. In one ormore embodiments, the RS is coupled to the plurality of lanes via aplurality of media-independent interfaces.

In another embodiment, the disclosure includes an apparatus in a passiveoptical network (PON). The apparatus includes a reconciliation sublayer(RS) configured to modify a preamble of a data packet to include anindicator associated with at least one lane to be used to transmit thedata packet. The apparatus further includes a transmitter coupled to theRS and configured to transmit the data packet in multiple fragments overa plurality of lanes, where the indicator is configured to identify afirst lane selected from the plurality of lanes and to identify at leastone fragment transmitted over the first lane.

In some embodiments, the RS is further configured to replicate theindicator into each lane within the plurality of lanes. In one moreembodiments, each indicator is configured to identify a respective setof fragments transmitted over a lane in which that indicator has beenreplicated. In one more embodiments, each indicator is furtherconfigured to indicate that fragments within the respective set offragments form part of the data packet. In one or more embodiments, thereplicated indicators are configured to identify at least one of: eachlane used to transmit the frames; frames transmitted over each lane;each frame associated with the data packet; and a lane order occupied bya particular frame. In one more embodiments, the apparatus furthercomprises a plurality of media-independent interfaces configured tointerconnect the RS to a plurality of physical layers. In one moreembodiments, the plurality of media-independent interfaces comprise aGigabit media-independent interface (GMII), a 10 GMII (XGMII), a 25 GMII(25G-MII), or any combination thereof

In yet another embodiment, the disclosure includes a non-transitorycomputer-readable medium storing computer instructions for implementinga method in a passive optical network (PON). The instructions forimplementing the method being such that when executed by one or moreprocessors, cause the one or more processors to perform the steps ofmodifying a preamble of a data packet to include an indicator associatedwith at least one lane to be used to transmit the data packet,fragmenting the data packet into frames, and transmitting the framesover a plurality of lanes. The indicator is configured to identify afirst lane selected from the plurality of lanes and to identify at leastone frame transmitted over the first lane.

In some embodiments, the instructions for implementing the method beingsuch that when executed by the one or more processors, cause the one ormore processors to perform the step of replicating the indicator intoeach lane within the plurality of lanes in response to fragmenting thedata packets into frames. In one or more embodiments, each indicator isconfigured to identify a respective set of frames transmitted over alane in which that indicator has been replicated. In one or moreembodiments, each indicator is further configured to indicate thatframes within the respective set of frames form part of the data packet.In one or more embodiments, the replicated indicators are configured toidentify at least one of: each lane used to transmit the frames; framestransmitted over each lane; each frame associated with the data packet;and a lane order occupied by a particular frame. In one or moreembodiments, a reconciliation sublayer (RS) is used to modify thepreamble to include the indicator, where the RS is coupled to theplurality of lanes via a plurality of media-independent interfaces.

For the purpose of clarity, any one of the foregoing embodiments may becombined with any one or more of the other foregoing embodiments tocreate a new embodiment within the scope of the present disclosure.

These and other features will be more clearly understood from thefollowing detailed description taken in conjunction with theaccompanying drawings and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of this disclosure, reference is nowmade to the following brief description, taken in connection with theaccompanying drawings and detailed description, wherein like referencenumerals represent like parts.

FIG. 1 is a schematic diagram of a PON.

FIG. 2 is a diagram of a frame structure according to an embodiment ofthe disclosure.

FIG. 3 is a schematic diagram of a channel bonding device according toan embodiment of the disclosure.

FIG. 4 is a diagram of a bonded frame according to an embodiment of thedisclosure.

FIG. 5 is a schematic diagram of a transmitter according to anembodiment of the disclosure.

FIG. 6 is a schematic diagram of a receiver according to an embodimentof the disclosure.

FIG. 7 depicts a flowchart of a method for transmitting data accordingto an embodiment of the disclosure.

FIG. 8 depicts a schematic diagram of a network unit according to anembodiment of the disclosure.

DETAILED DESCRIPTION

It should be understood at the outset that, although an illustrativeimplementation of one or more embodiments are provided below, thedisclosed systems and/or methods may be implemented using any number oftechniques, whether currently known or in existence. The disclosureshould in no way be limited to the illustrative implementations,drawings, and techniques illustrated below, including the exemplarydesigns and implementations illustrated and described herein, but may bemodified within the scope of the appended claims along with their fullscope of equivalents.

Disclosed herein are embodiments for using an inverse multiplexingscheme such as channel bonding to achieve increased data rates in a PON.To this end, a plurality of data packets may be fragmented andtransmitted over multiple lanes (e.g., multiple transmission lines orchannels) bonded to one another, where a preamble of a data packet maybe modified to include channel bonding information. The channel bondinginformation within the modified preamble may identify different datapackets and/or fragments, as well as distinct lanes through which eachdata packet/fragment is transmitted. Further, the inverse multiplexingscheme may support communications where bonded channels may be combinedwith non-bonded channels such as in a same optical distribution network(ODN).

FIG. 1 is a schematic diagram of a passive optical network (PON) 100 forimplementing embodiments of the present disclosure. The PON 100 maycomprise an optical line terminal (OLT) 110, one or more optical networkunits (ONUs) 120, and an ODN 130 configured to couple the OLT 110 to theONUs 120. While four ONUs are depicted in FIG. 1, the PON 100 maycomprise more or less ONUs 120 in other implementations.

The PON 100 may be configured as a communications network that may notrequire active components to distribute data between the OLT 110 and theONUs 120. Instead, the PON 100 may use passive optical components in theODN 130 to distribute data between the OLT 110 and the ONUs 120. The PON100 may comprise any suitable network such as a next-generation PON(NG-PON), an NG-PON1, an NG-PON2, a gigabit-capable PON (GPON), a 10gigabit per second PON (XG-PON), an Ethernet PON (EPON), a 10 gigabitper second EPON (10G-EPON), a next-generation EPON (NG-EPON), awavelength-division multiplexing (WDM) PON, a time- andwavelength-division multiplexing (TWDM) PON, point-to-point (P2P) WDMPONs (P2P-WDM PONs), an asynchronous transfer mode PON (APON), abroadband PON (BPON), etc.

An EPON is a PON standard developed by the Institute of Electrical andElectronics Engineers (IEEE) and specified in IEEE 802.3, which isincorporated herein by reference as if reproduced in its entirety. InEPON, a single fiber can be used for both the upstream and thedownstream transmission with different wavelengths. The OLT 110 mayimplement an EPON Media Access Control (MAC) layer for transmission ofEthernet frames, while a Multi-Point Control Protocol (MPCP) may beimplemented to perform bandwidth assignment, bandwidth polling,auto-discovery, ranging, and the like. Ethernet frames may be broadcastdownstream based on a Logical Link Identifier (LLID) embedded in apreamble frame. Upstream bandwidth may be assigned based on the exchangeof signals (e.g., Gate and Report messages) between the OLT 110 and anONU 120.

The OLT 110 is configured to communicate with the ONUs 120 and anothernetwork (not shown). Specifically, the OLT 110 may act as anintermediary between the other network and the ONUs 120. For instance,the OLT 110 may forward data received from the other network to the ONUs120, and forward data received from the ONUs 120 to the other network.The OLT 110 may comprise at least one transmitter and receiver. Inscenarios where the other network uses a network protocol different fromthe protocol used in the PON 100, the OLT 110 may comprise a converterfor converting the network protocol to the PON protocol, and vice versa.The OLT 110 is typically located at a central location such as a centraloffice (CO), but it may also be located at other suitable locations.

In some implementations, the ODN 130 may be a data distribution systemthat includes optical fiber cables, couplers, splitters, distributors,and/or other equipment. Such components may include passive opticalcomponents that do not require power to distribute data signals betweenthe OLT 110 and the ONUs 120. Alternatively, one or more componentswithin the ODN 130 may take the form of active (e.g., powered)components such as optical amplifiers. The ODN 130 may typically extendfrom the OLT 110 to the ONUs 120 in a branching configuration as shown,but the ODN 130 may be configured in any other suitablepoint-to-multipoint (P2MP) configuration.

In an embodiment, the ODN 130 may comprise an optical splitter 125located between the OLT 110 and ONUs 120. The splitter 125 may be anysuitable device for splitting a combination of optical signals andforwarding the split signals to the ONUs 120. The splitter 125 may alsobe any suitable device for receiving signals from the ONUs 120,combining those signals into a combined received signal, and forwardingthe combined received signal to the OLT 110. For example, the splitter125 may split a downstream optical signal into n split downstreamoptical signals in the downstream direction (e.g., from the OLT 110 tothe ONUs 120), and combine n upstream optical signals into one combinedupstream optical signal in the upstream direction (e.g., from the ONUs120 to the OLT 110), where n is equal to the number of ONUs 120. In someaspects, the OLT 110 may comprise a bi-directional optical amplifier(OA) to amplify a combined transmitted signal as needed in order toforward the combined transmitted signal to the splitter 125, and toreceive a combined signal from the splitter 125 and amplify the combinedreceived signal as needed.

The ONUs 120 may communicate with the OLT 110 and a customer or user(not shown), and the ONUs 120 may act as an intermediary between the OLT110 and the customer. For instance, the ONUs 120 may forward data fromthe OLT 110 to the customer, and forward data from the customer to theOLT 110. The ONUs 120 may comprise an optical transmitter fortransmitting optical signals to the OLT 110 and an optical receiver forreceiving optical signals from the OLT 110. The ONUs 120 may furthercomprise a converter that converts optical signals into electricalsignals and converts electrical signals into optical signals. In someaspects, the ONUs 120 may comprise a second transmitter that transmitsthe electrical signals to the customer and a second receiver thatreceives electrical signals from the customer. ONUs 120 and opticalnetwork terminals (ONTs) are similar, and thus the terms may be usedinterchangeably herein. The ONUs 120 may typically be located atdistributed locations such as customer premises, but they may also belocated at other suitable locations.

In NG-PON systems, data rates may be expected to reach or exceed about25 Gigabits per second (Gb/s) over a single wavelength (or channel), andabout 50 Gb/s or 100 Gb/s over two or four 25 Gb/s wavelengths,respectively. Due to optical limitations, supporting such data rates inNG-PONs may be challenging, even when using higher-level modulationschemes such as three-level (3-level) duobinary and pulse amplitudemodulation (PAM) with four amplitude levels (PAM-4). To achieve higherdata rates, an NG-PON may employ a link aggregation scheme such asdefined by the Electrical and Electronics Engineers (IEEE) 802.1adstandard, which is incorporated herein by reference. For example, such ascheme typically involves aggregating multiple links together to form alink aggregation group (LAG), in which case an entity such as MediumAccess Control (MAC) client may treat the LAG as a single link.

While link aggregation schemes may increase data rates by combininglimited rates of individual links, a typical LAG may only reach about40-60% of the aggregated link capacity. Moreover, link aggregationschemes often employ hashing algorithms to distribute or route trafficamong links of the LAG based on fields such as destination and sourceMAC addresses. For example, in a point-to-point topology where there isa single source MAC address and a single destination MAC address,traditional hashing algorithms may result in hashing the source anddestination MAC addresses such that all traffic is output to the sameport. Consequently, data traffic may not be effectively distributed insuch cases. Furthermore, link aggregation schemes may need multiple MACinstances (e.g., clients, protocol stacks, etc.) to communicate dataover LAGs.

In an alternative approach, whole-sized packet frames may be transmittedover individual lanes. This approach may include monitoring the time ofarrival of a frame and then reordering packets according to theiroriginal order based on the arrival time of the first packet (or byte ofthe first packet). However, this approach may demand a significantamount of buffering at the OLT 110 and ONU 120. In addition, undesirabledelays may be incurred by transmitting whole-sized packet frames. Bycomparison, buffer requirements and/or transmission delays may beminimized by fragmenting data packets into relatively small frames andtransmitting the fragmented frames over multiple lanes rather than anindividual lane.

In an embodiment, the PON 100 may employ an inverse multiplexing schemesuch as channel bonding to achieve increased data rates as compared tothat achievable over a single optical channel. Specifically, datapackets may be fragmented into a plurality of frames and transmittedover multiple lanes using a modified preamble, which may improve overallperformance as compared to conventional approaches such as linkaggregation. For example, the disclosed embodiments may provideaggregation at close to full link capacity, while maintaining latencycommensurate with that expected from a link of capacity. Moreover, thesefeatures may be realized using a single MAC instance. Further, the PON100 may be built on existing EPON protocols, thus requiring minimalmodification. The PON 100 may also be optimized for NG-PON standardssuch as NG-PON2 and NG-EPON, which may include WDM, TDM, and/or TWDMschemes. While the disclosed embodiments may generally focus on PONs,the embodiments apply to any Ethernet or other access networks.

Table 1 below depicts an example of a preamble according to atraditional Ethernet frame. Briefly, a traditional Ethernet frametypically comprises a preamble having seven bytes of hexadecimal values(0x55), which make up the first field of an Ethernet packet. The eighthbyte includes a start of frame delimiter (SFD) value (0xd5) thatindicates the end of the preamble and the beginning of the Ethernetframe.

TABLE 1 8 Bytes Preamble Field Preamble/SFD 1 — 0x55 2 — 0x55 3 — 0x55 4— 0x55 5 — 0x55 6 — 0x55 7 — 0x55 8 SFD 0xd5

Referring now to FIG. 2, a diagram is depicted of a frame structure 200comprising a modified preamble 210, which may be part of a messageexchanged between the OLT 110 and ONUs 120. As discussed further withrespect to FIG. 3, a frame structure 200 such as depicted in FIG. 2 mayinclude various data bits and characters following the modified preamble210. In general, the frame structure 200 may correspond to part of anEthernet frame that the PON 100 may employ when implemented as an EPON.In such implementations, the preamble 210 may be modified pursuant toIEEE standards such as IEEE 802.3ca, which is incorporated herein byreference. As shown in column/lane 1.2 of the frame structure 200, thethird byte of the modified preamble 210 may include a start of logicallink identifier (LLID) delimiter (SLD) value (0xd5). The SLD is anEPON-specific replacement for the traditional Ethernet SFD (0xd5)transmitted in the eighth byte of the preamble. In addition, the sixthand seventh bytes of the modified preamble 210 may include an LLIDfollowed by a cyclic redundancy check 8 (CRC8), which is an 8-biterror-detection code calculated as a function of the first bit of theSLD through the last bit of the LLID. In implementations where the framestructure 200 is used for transmissions over point-to-point (P2P) links,the LLID in the sixth and seventh bytes of the preamble 210 may not benecessary, and thus replaced with other fields, e.g., hexadecimal values(0x55).

In an embodiment, the modified preamble 210 may include a channelbonding indication (CBI) field. While the CBI field is depicted in thefifth byte of the preamble 210 at column/lane 2.0, the CBI field may belocated in a different byte in other implementations. For example, theCBI field may be located in the fourth byte of the preamble 210 atcolumn/lane 1.3, in which case the fifth byte of the preamble 210 atcolumn/lane 2.0 may simply include a hexadecimal value (0x55). Inaddition, while the CBI field may occupy an 8-bit field, the size of theCBI value may depend on the number of lanes (or channels) to be linked.For instance, a CBI value comprising three to four bits may besufficient if the number of lanes is equal to two or four, while morebits may be necessary for data transmissions over a greater number oflanes. The size of the CBI value may also depend on the data rate ofeach lane.

In some aspects, the CBI field may serve at least three purposes. First,the CBI field may indicate that a particular frame is part of a bondedMAC frame. Second, the CBI field may identify the lane order occupied bythis particular part of the bonded MAC frame. Third, the CBI field mayserve as a synchronization indicator to assist a receiver with aligningfragmented packets in a proper order. Additionally or alternatively, theCBI field may indicate whether data fragments in different lanes areassociated with the same or different LLIDs.

FIG. 3 depicts an embodiment of a channel bonding device 300, which maybe implemented by the OLT 110 and each ONU 120. The channel bondingdevice 300 may comprise a datalink layer 305 including a MAC ormultipoint MAC Control 310 such as a Multi-Point Point Control Protocol(MPCP), and one or more MAC sublayers 315 coupled to a reconciliationsublayer (RS) 320. In a conventional PON system, the channel bondingdevice 300 may employ a single media independent interface (MII) tointerconnect the datalink layer 305 to a physical layer, which mayinclude a physical coding sublayer (PCS), a forward error correction(FEC) sublayer, a physical-medium-attachment (PMA) sublayer, and aphysical-medium-dependent (PMD) sublayer.

In an embodiment, the RS 320 may be enhanced to interface with multiplephysical layers 325-1 . . . 325-N via a number N of MIIs 350, where N isa positive integer greater than one. The MMI 350 may be implemented asany suitable interface such as a Gigabit MMI (GMII), 10 GMII (XGMII), 25GMII (25G-MII), etc. For instance, if the PON 100 comprises a 100G-PON,N MIIs 350 may comprise four 25G-MIIs for data transmissions over up tofour lanes. In some implementations, N MIIs 350 may comprise differenttypes of interfaces. For example, the RS 320 may interface with onephysical layer 325-1 via a GMII and interface with another physicallayer 325-N via a 25G-MII. The physical layers 325-1 . . . 325-N mayinclude respective PCSs 330-1 . . . 330-N, FEC sublayers 335-1 . . .335-N, PMA sublayers 340-1 . . . 340-N, and PMD sublayers 345-1 . . .345-N, which may each interface with a medium 355 (e.g., fiber opticmedia) through a medium-dependent interface (MDI) 360. In otherimplementations, the physical layers 325-1 . . . 325-N may include moreor less sublayers.

Notably, the channel bonding device 300 may be implemented with existingand/or future PON protocols with minimal changes. For instance, nochanges may be needed to the MAC Control 310 and MAC sublayers 315,while no changes beyond those expected may be needed to the PCSs 330-1 .. . 330-N, FEC sublayers 335-1 . . . 335-N, PMA sublayers 340-1 . . .340-N, and/or PMD sublayers 345-1 . . . 345-N. The functions of the MACControl 310, MAC sublayers 315, PCS sublayers 330-1 . . . 330-N, FECsublayers 335-1 . . . 335-N, PMA sublayers 340-1 . . . 340-N, PMDsublayers 345-1 . . . 345-N, and MDI 360 are well known to those ofordinary skill in the art. Therefore, discussion of these elements willbe limited to the extent necessary for enabling a proper understandingof the present disclosure.

Generally, the MAC Control 310 protocol may perform bandwidthallocation, bandwidth polling, auto-discovery, ranging, dataencapsulation, etc. The MAC sublayers 315 may provide addressing andchannel access services to the physical layers 325-1 . . . 325-N andsublayers thereof The PCS sublayers 330-1 . . . 330-N may performencoding, multiplexing, and synchronization of outgoing data streams.The FEC sublayers 335-1 . . . 335-N may perform error control byinserting parity bits into frames received from the N MMIs 350 fortransmission. The PMA sublayers 340-1 . . . 340-N may support theexchange of code-groups between PCS entities, convert such code-groupsinto bits, and pass the bits to the PMD sublayers 345-1 . . . 345-N (andvice versa). The PMD sublayers 345-1 . . . 345-N may provide aninterface from the PMA sublayers 340-1 . . . 340-N to the transmissionmedium 355.

In operation, the channel bonding device 300 may receive (e.g., at RS320) a request to transmit data from a MAC client 370 implemented in orat the datalink layer 305. In turn, data from one or more MAC layers 315may be input to the RS 320, which may add a CBI field to a modifiedpreamble 210 (see FIG. 2) for bonded channels at a transmitter. Whenreceiving data packets, the RS 320 may use the CBI field to reassembledata packets in a proper order at a receiver. If multiple fragments of adata packet are received (e.g., via N MMIs 350), the RS 320 may use theCBI field to reconstruct the data packet, which may then be delivered tothe MAC client via one of the MAC layers 310. As discussed further belowwith respect to FIGS. 5 and 6, the channel bonding device 300 maycomprise one or more transceiver units to perform such operations.

FIG. 4 depicts an example of a bonded frame 400 transmitted by thechannel bonding device 300 over an interface (e.g., MII 350) comprisingmultiple channels (or lanes). While this example may be based onstripping data across an XGMII comprising four lanes numbered 1through4, other examples may employ any suitable interface comprising the sameor different number of lanes. In addition, rather than striping data interms of bits or bytes, data may be striped by words (e.g., multiplebytes), or by code words (e.g., FEC code words). For example, if the PON100 comprises a 10G-EPON, code words may include a Reed-Solomon codeword such as RS(255,223).

When transmission of the bonded frame 400 is initiated, the RS 320 maycopy a modified preamble (e.g., preamble 210) into each of the fourlanes in rows 1 and 2, where each modified preamble may include a CBIfield that identifies a specific lane associated with that modifiedpreamble. Next, the RS 320 may stripe data packets across the fourlanes, beginning with a first data byte (d1) transmitted via lane 1 incolumn 1 of row 3 and ending with a last data byte (d70) transmitted vialane 2 in column 2 of row 7. In some aspects, the RS 320 may divide datapackets into fragments (e.g., 32-byte fragments for an XGMII) and thenassign the fragmented data packets to each of the four lanes in a roundrobin fashion.

In FIG. 4, the last data packet transmitted in each of the four lanesmay be followed by a terminate symbol /T/. That is, data transmitted inlane 1 terminates in column 1 of row 8; data transmitted in lane 2terminates in column 3 of row 7; data transmitted in lane 3 terminatesin column 1 of row 7; and data transmitted in lane 4 terminates incolumn 1, row 7. In some cases, symbols following each /T/ symbol may befilled with one or more idle characters /I1/, such as to maintaincompatibility with a current definition of the MMI. For instance, idlecharacters may be necessary in order for data transmitted via the lanesto get across the MMI.

While the number of idle characters may vary in other examples (e.g.,depending on implementation), FIG. 4 depicts an example using four idlecharacters /I1/, /I2/, /I3/, /I4/. In lane 2 of this example, the /T/symbol is followed by a first idle character /I1/ in column 4 of row 7,while the remaining three idle characters /I2/, /I3/, /I4/ in lane 2occupy columns 1-3 of row 8. In lanes 3 and 4, the first three idlecharacters 41/ /12/, /13/ occupy column 2-4 of row 7, while the fourthidle character /I4/ in lanes 3 and 4 occupies column 1 in row 8. In lane1, the first three idle characters /I2/, /I3/, /I4/ occupy columns 2-4of row 8, while the fourth idle character /I4/ in lane 1 occupies column1 of row 9.

In some implementations, one or more stuffing idle characters /i/ may beadded, e.g., to justify or align all four lanes, avoid misinterpretationof data, etc. For instance, following the fourth idle character /I4/ inlane 1, three stuffing idle characters /i/ may be added in columns 2-4of row 9. In lane 2, one stuffing idle character /i/ may be added incolumn 4 of row 8, while four stuffing idle characters /i/ may be addedin columns 1-4 of row 9. In lanes 3 and 4, three stuffing idlecharacters /i/ may be added in columns 2-4 of row 8, while four stuffingidle characters /i/may be added in columns 1-4 of row 9. Further, theidle characters /I/ and/or stuffing idle characters /i/ discussed hereinmay be supplied by the datalink layer 305 (e.g., via MAC Control 310).Lastly, row 10 comprises the next opportunity to begin a new data frametransmission (e.g., in lane 2).

Referring now to FIG. 5, a block diagram is depicted of a transmitter500 according to an embodiment of the disclosure. The transmitter 500may be implemented in various entities disclosed herein such as the OLT110 and/or ONUs 120. The transmitter 500 may comprise an input/output(I/O) block 505, which may be implemented by the RS 320 in FIG. 3. Inaddition, a MAC entity such as the MAC client 370 in FIG. 3 may initiatetransmission by communicating a data request signal to the I/O block 505via one of the MAC layers 310. In FIG. 5, an example of such a datarequest signal is denoted as MAC:MA_DATA.request, which may specifyvarious information such as a destination address (DA), a source address(SA), size of a MAC service data unit (m_sdu), etc. According to oneimplementation, the I/O block 505 may comprise a preamble replacementand idle insertion block 505 configured to replace a preamble and SFD ofa standard Ethernet frame (e.g., see Table 1) with an EPON-specificpreamble as previously discussed with respect to FIG. 2. As a result,the third byte of the replaced preamble may include an SLD value, whilethe sixth and seventh bytes may include an LLID followed by a CRC8.

The preamble replacement and idle insertion block 505 may also beconfigured to insert a CBI field in either the fourth or the fifth byteof the replaced preamble to generate a modified preamble such asdepicted in FIG. 2. The preamble replacement and idle insertion block505 may then replicate the CBI field based on a number of channels (orlanes) through which the LLID is to be transmitted. For example, thedata request signal from the MAC client and/or input received fromanother source may include provisioning information indicating a numberof LLIDs and a number of channels to be used by each LLID, e.g., oneLLID may be transmitted via one channel, while another LLID may betransmitted via two channels, four channels, etc. If one LLID is to betransmitted across two channels, the preamble replacement and idleinsertion block 505 may replicate that LLID twice. Likewise, if one LLIDis to be transmitted across four channels, the preamble replacement andidle insertion block 505 may replicate that LLID four times.

In some aspects, the preamble replacement and idle insertion block 505may also replicate a Terminate control character /T/ in a similar manneras the LLID. Thus, if one LLID is to be transmitted via two channels,the replication performed by the preamble replacement and idle insertionblock 505 may be such that the LLID and Terminate control character /T/would be repeated in each of the two channels used to transmit data(e.g., an Ethernet frame). Likewise, if an LLID were to be transmittedacross four channels, the LLID and Terminate control character /T/ wouldbe repeated four times.

The preamble replacement and idle insertion block 505 may be coupled toa channel distribution logic block 510 configured to distribute databased on a ChannelBinding signal generated by the preamble replacementand idle insertion block 505. For example, the ChannelBinding signal maycause the channel distribution logic block 510 to distribute data (e.g.,headers, trailers, data frames, etc.) through a multiplexer 515 to nfirst-in first-out (FIFO) FIFO(1) . . . FIFO(n) buffers 520, where n isa positive integer greater than one. In FIG. 5, the FIFO(1) . . .FIFO(n) buffers 520 correspond to a distinct channel such as one of thefour lanes discussed with respect to FIG. 4. In this case, the distinctchannel corresponding to each FIFO(1) . . . FIFO(n) buffer may berepresented as channel(1) . . . channel(n).

Once the beginning of a bonded data frame is identified using acorresponding CBI field in the modified preamble generated by thepreamble replacement and idle insertion block 505, the bonded data framemay be divided into a plurality of equally sized fragments. Based on theChannelBinding signal received from the preamble replacement and idleinsertion block 505, the channel distribution logic block 510 may outputa ChannelSelect signal to the multiplexer 515 such that one of the datafragments is delivered to an appropriate channel via one of the FIFO(1). . . FIFO(n) buffers 520. In some aspects, the ChannelSelect signalsoutputted to the multiplexer 515 may be such that the FIFO(1) . . .FIFO(n) buffers 520 deliver data to each channel(1) . . . channel(n) ina round robin fashion.

Additionally or alternatively, the FIFO(1) . . . FIFO(n) buffers 520 maybe configured to align data frames for synchronous transfer over ninterfaces XGMII(1) . . . XGMII(n), e.g., to physical layers 325-1 . . .325-N (where n=N). Furthermore, data transmission rate may be controlledby a clock (Clk) signal, such as an XGMII Clk signal that may be usedwhen implementing the PON 100 as an XG-PON. As previously mentioned, thePON 100 may be implemented as any suitable type of PON, and any suitableinterface may be used. Thus, the present embodiments are not limited toclock signals and interfaces such as depicted in FIG. 5.

Referring now to FIG. 6, a block diagram is depicted of a receiver 600according to an embodiment of the disclosure. Like the transmitter 500,the receiver 600 may be implemented in various entities disclosed hereinsuch as the OLT 110 and/or ONUs 120. For example, at least onetransmitter 500 may be implemented in the OLT 110 for downlinktransmissions to an ONU 120, in which case at least one receiver 600 maybe implemented in the ONU 120 to receive data from the OLT 110.Similarly, at least one transmitter 500 may be implemented in the ONU120 for uplink transmissions to the OLT 110, in which case at least onereceiver 600 may be implemented in the OLT 110 to receive data from theONU 120. In some aspects, the transmitter 500 and receiver 600 combinedinto a single transceiver unit implemented in the OLT 110 and/or ONUs120.

The receiver 600 may comprise a plurality of I/O blocks 605(1) . . .605(n) for receiving data from the transmitter 500 via XGMII(1) . . .XGMII(n). According to one implementation, the n interfaces in FIGS. 5and 6 may comprise a mixture of different interfaces. That is, one ormore of the interfaces (e.g., an XGMII(2)) may be replaced with adifferent type of interface (e.g., GMII). Upon receiving data frames viaXGMII(1) . . . XGMII(n), the input blocks 605(1) . . . 605(n) may removeexcess idle code words or idle symbols (e.g., /I/ and /i/) that wereinserted (i.e., at the transmitter), as well as any duplicate headersand trailers (e.g., CBI and /T/) that were replicated by the I/O 505. Inaddition, the input blocks 605(1) . . . 605(n) may detect preamblesmodified by the I/O 505 and replace them with another preamble, e.g., inorder to be recognized by the MAC Control 310 and/or MAC sublayers 315.More specifically, each input block 605(1) . . . 605(n) may convert amodified preamble into its original form, such as a MAC preamble havingseven hexadecimal bytes followed by an SFD byte.

The receiver 600 may further comprise a memory management interface(MMI) 610 coupled to the input blocks 605(1) . . . 605(n), which mayextract LLID and CBI values from each modified preamble and pass thosevalues to the MMI 610. Among other things, the MMI 610 may controloperation of a cross point switch 615 such as to ensure a non-blockinginterface is provided from the I/O blocks 605 to FIFO(1) . . . FIFO(m)buffers 630, where m may be a positive integer equal to a number ofactive LLIDs. For instance, the cross point switch 615 may configured asan n×m switch (n-input, m-output), where any one of the n inputs may bedirected to any one of the m outputs. If a cross point switch does notoperate properly, a blocking scenario may occur if the cross pointswitch directs an input to one FIFO that blocks another input fromgetting to another FIFO. Accordingly, the MIM 610 may control operationof the cross point switch 615 to prevent such blocking scenarios.

Moreover, the MMI 610 may be configured to control data distribution tothe FIFO (1) . . . FIFO(m) buffers 630 based on a ChannelBinding signal,such as discussed with respect to FIG. 5. For instance, the MMI 610 mayuse the LLID and CBI values to ensure incoming data fragments areproperly distributed from the I/O blocks 605 to the FIFO (1) . . .FIFO(m) buffers 630, where m is a positive integer. For example,assuming each LLID may correspond to only one of the FIFO(1) . . .FIFO(m) buffers 630, the MMI 610 may direct data fragments associatedwith a particular frame to one of the FIFO(1) . . . FIFO(m) buffers 630.Based on the LLID and CBI values, the MMI 610 may determine when alldata fragments necessary to complete a data frame have been queued inone of the FIFO(1) . . . FIFO(m) buffers 630. In turn, the MMI 610 maygenerate a selection signal that causes a multiplexer 620 to select oneof the FIFO (1) . . . FIFO(m) buffers 630 containing data fragments of acomplete frame. For example, if the first FIFO(1) buffer is selected,the FIFO(1) buffer may release the data fragments in an appropriateorder to reconstruct the completed frame, which may be stored in abuffer 625. The receiver 600 may then generate a MAC signal to inform aMAC entity that a recovered data frame has been received. In FIG. 6, theMAC signal is denoted by MAC:MA_DATA.indication, which the receiver 600may use to send data (e.g., from RS 320) to the MAC entity (e.g., MACControl 310).

FIG. 7 depicts a method 700 of transmitting data packets over aplurality of data lanes according to an embodiment of the disclosure.The operations may be performed in the order shown, or in a differentorder. Further, two or more of the operations may be performedconcurrently instead of sequentially. In general, the method 700 may beimplemented by both the OLT 110 and ONUs 120 to perform downlink anduplink transmissions, respectively (e.g., using transmitter 500).Moreover, the method 700 may initiate when a MAC entity (e.g., MACControl 31) sends the RS 320 (e.g., via I/O unit 505) a request totransmit data (e.g., via MAC:MA_DATA.request signal in FIG. 5).

The method 700 commences at block 702, where a preamble of a data packetmay be modified to include a channel bonding indicator (CBI). At block704, the method 700 may fragment the data packet into a plurality ofdata frames. In some aspects, the data packet may be fragmented intoequally sized data frames. In other aspects, the data packet may befragmented into data frames having different sizes. At block 706, themethod 700 may transmit the plurality of data frames over a plurality oflanes. As previously discussed, the CBI may comprise various informationthat may be used to improve transmissions over multiple lanes, e.g., viamethod 700. As one example, the CBI may indicate that a particular frameis part of a data packet that has been fragmented. In addition, the CBImay identify a lane order occupied by this particular frame.Furthermore, the CBI may indicate whether fragmented data frames indifferent lanes are associated with the same or different LLIDs.

FIG. 8 depicts a schematic diagram of a network device 800 according toan embodiment of the disclosure. The network device 800 is suitable forimplementing the disclosed embodiments as described herein. For example,the network device 800 may be implemented as the OLT 110, as the ONU120, and/or as any other component disclosed herein. The device 800comprises ingress ports 810 and a receiver unit or units (Rx) 820 forreceiving data; a processor, microprocessor, logic unit, or centralprocessing unit (CPU) 830 configured to process the data; a transmitterunit or units (Tx) 840 and egress ports 850 for transmitting the data;and a memory 860 for storing the data. The network device 800 may alsocomprise optical-to-electrical (OE) components and electrical-to-optical(EO) components coupled to the ingress ports 810, the receiver units820, the transmitter units 840, and/or the egress ports 850 for egressor ingress of optical or electrical signals.

The processor 830 may be implemented by hardware and/or software. Theprocessor 830 may be implemented as one or more CPU chips, cores (e.g.,as a multi-core processor), field-programmable gate arrays (FPGAs),application specific integrated circuits (ASICs), or digital signalprocessors (DSPs). The processor 830 may be communicatively linked tothe ingress ports 810, receiver units 820, transmitter units 840, egressports 850, and/or memory 860.

The processor 830 comprises a channel bonding module 870 configured toimplement the embodiments disclosed herein, including method 700. Theinclusion of the channel bonding module 870 may therefore provide asubstantial improvement to the functionality of the network device 800and effects a transformation of the network device 800 to a differentstate. Alternatively, the channel bonding module 870 may be implementedas readable instructions stored in the memory 860 and executable by theprocessor 830. The network device 800 may include any other means forimplementing the embodiments disclosed herein, including method 700.

The memory 860 comprises one or more disks, tape drives, or solid-statedrives and may be used as an over-flow data storage device, to storeprograms when such programs are selected for execution, or to storeinstructions and data that are read during program execution. The memory860 may be volatile or non-volatile and may be read-only memory (ROM),random-access memory (RAM), ternary content-addressable memory (TCAM),or static random-access memory (SRAM).

In an embodiment, the disclosure includes means for implementing amethod at a transmitter in a passive optical network (PON). Thetransmitter includes means for modifying a preamble of a data packet toinclude an indicator associated with at least one lane to be used totransmit the data packet. The transmitter further includes means forfragmenting the data packet into frames, and means for transmitting theframes over a plurality of lanes, where the indicator is configured toidentify a first lane selected from the plurality of lanes and toidentify at least one frame transmitted over the first lane.

In an embodiment, the disclosure includes means for implementing anapparatus in a passive optical network (PON). The apparatus includesmeans for modifying a preamble of a data packet to include an indicatorassociated with at least one lane to be used to transmit the datapacket. The apparatus further includes means for transmitting the datapacket in multiple fragments over a plurality of lanes, where theindicator is configured to identify a first lane selected from theplurality of lanes and to identify at least one fragment transmittedover the first lane. In some aspects, the apparatus includes areconciliation sublayer (RS) having means for modifying the preamble ofthe data packet to include the indicator. In additional or alternativeaspects, the apparatus includes a transmitter having means fortransmitting the data packet in multiple fragments.

In an embodiment, the disclosure includes one or more means forexecuting computer instructions on a non-transitory computer-readablemedium to implement a method in a passive optical network (PON). The oneor more means including means for modifying a preamble of a data packetto include an indicator associated with at least one lane to be used totransmit the data packet. The one more means further including means forfragmenting the data packet into frames, and means for transmitting theframes over a plurality of lanes, where the indicator is configured toidentify a first lane selected from the plurality of lanes and toidentify at least one frame transmitted over the first lane.

While several embodiments have been provided in the present disclosure,it may be understood that the disclosed systems and methods might beembodied in many other specific forms without departing from the spiritor scope of the present disclosure. The present examples are to beconsidered as illustrative and not restrictive, and the intention is notto be limited to the details given herein. For example, the variouselements or components may be combined or integrated in another systemor certain features may be omitted, or not implemented.

In addition, techniques, systems, subsystems, and methods described andillustrated in the various embodiments as discrete or separate may becombined or integrated with other systems, modules, techniques, ormethods without departing from the scope of the present disclosure.Other items shown or discussed as coupled or directly coupled orcommunicating with each other may be indirectly coupled or communicatingthrough some interface, device, or intermediate component whetherelectrically, mechanically, or otherwise. Other examples of changes,substitutions, and alterations are ascertainable by one skilled in theart and may be made without departing from the spirit and scopedisclosed herein.

What is claimed is:
 1. A method implemented at a transmitter in a passive optical network (PON), the method comprising: modifying a preamble of a data packet to include an indicator associated with at least one lane to be used to transmit the data packet, the preamble comprising the indicator and a logical link identifier (LLID); fragmenting the data packet into frames; and transmitting the frames over a plurality of lanes; the indicator identifying a first lane selected from the plurality of lanes and identifying at least one frame transmitted over the first lane, with the indicator indicating for a frame that the frame is part of a bonded Media Access Control (MAC) frame.
 2. The method of claim 1, with the indicator further identifying a lane order occupied by the part of the bonded MAC frame.
 3. The method of claim 1, further comprising, responsive to fragmenting the data packets into frames, replicating the indicator into each lane within the plurality of lanes.
 4. The method of claim 1, wherein the transmitter comprises a reconciliation sublayer (RS), with the RS modifying the preamble to include the indicator.
 5. The method of claim 3, wherein each indicator is configured to identify a respective set of frames transmitted over a lane in which that indicator has been replicated.
 6. The method of claim 3, wherein the replicated indicators are configured to identify at least one of: each lane used to transmit the frames; frames transmitted over each lane; each frame associated with the data packet; or a lane order occupied by a particular frame.
 7. The method of claim 4, wherein the RS is coupled to the plurality of lanes via a plurality of media-independent interfaces.
 8. The method of claim 5, wherein each indicator is further configured to indicate that frames within the respective set of frames form part of the data packet.
 9. An apparatus in a passive optical network (PON), the apparatus comprising: a reconciliation sublayer (RS) configured to modify a preamble of a data packet to include an indicator associated with at least one lane to be used to transmit the data packet, the preamble comprising the indicator and a logical link identifier (LLID); and a transmitter coupled to the RS and configured to transmit the data packet in multiple fragments over a plurality of lanes, the indicator identifying a first lane selected from the plurality of lanes and identifying at least one fragment transmitted over the first lane, with the indicator indicating for a frame that the frame is part of a bonded Media Access Control (MAC) frame.
 10. The apparatus of claim 9, with the indicator further identifying a lane order occupied by the part of the bonded MAC frame.
 11. The apparatus of claim 9, wherein the RS is further configured to replicate the indicator into each lane within the plurality of lanes responsive to fragmenting the data packets into frames.
 12. The apparatus of claim 11, wherein each indicator is configured to identify a respective set of frames transmitted over a lane in which that indicator has been replicated.
 13. The apparatus of claim 11, wherein the replicated indicators are configured to identify at least one of: each lane used to transmit the frames; frames transmitted over each lane; each frame associated with the data packet; or a lane order occupied by a particular frame.
 14. The apparatus of claim 12, wherein each indicator is further configured to indicate that frames within the respective set of frames form part of the data packet.
 15. A non-transitory computer-readable medium storing computer instructions for implementing a method in a passive optical network (PON), that when executed by one or more processors, cause the one or more processors to perform the steps of: modifying a preamble of a data packet to include an indicator associated with at least one lane to be used to transmit the data packet, the preamble comprising the indicator and a logical link identifier (LLID); fragmenting the data packet into frames; and transmitting the frames over a plurality of lanes, the indicator identifying a first lane selected from the plurality of lanes and identifying at least one frame transmitted over the first lane, with the indicator indicating for a frame that the frame is part of a bonded Media Access Control (MAC) frame.
 16. The non-transitory computer-readable medium of claim 15, with the indicator further identifying a lane order occupied by the part of the bonded MAC frame.
 17. The non-transitory computer-readable medium of claim 15, wherein the instructions for implementing the method in the PON, that when executed by the one or more processors, cause the one or more processors to further perform the steps of replicating the indicator into each lane within the plurality of lanes responsive to fragmenting the data packets into frames.
 18. The non-transitory computer-readable medium of claim 15, wherein each indicator is configured to identify a respective set of frames transmitted over a lane in which that indicator has been replicated.
 19. The non-transitory computer-readable medium of claim 15, wherein the replicated indicators are configured to identify at least one of: each lane used to transmit the frames; frames transmitted over each lane; each frame associated with the data packet; or a lane order occupied by a particular frame.
 20. The non-transitory computer-readable medium of claim 18, wherein each indicator is further configured to indicate that frames within the respective set of frames form part of the data packet. 